An injection nozzle is exposed, in use, to the temperature within the engine cylinder or other combustion space. As a result, the parts of the injection nozzle which are exposed to such temperatures, for example the seating surface, must be able to withstand such temperatures without significant degradation which would otherwise result in an undesirable reduction in the service life of the injection nozzle. Further, the deposition of fuel lacquer within the injection nozzle, which can undesirably effect, for example, the fuel flow rate through the injector, is accelerated where the nozzle is exposed to high operating temperatures.
In a known arrangement, in order to protect an injection nozzle from degradation resulting from the temperature within the cylinder or combustion space, a heat shield in the form of a tubular member is provided, the heat shield surrounding a part of the injection nozzle, shielding that part of the nozzle from combustion flames, in use, and conducting heat away from the injection nozzle. Although such an arrangement may result in the service life of the injection nozzle being increased, the provision of the additional heat shield results in the arrangement being relatively complex. Further, in some arrangements, insufficient space may be available to permit the use of such a heat shield.